Technical Field
The present invention relates to a garden tool, in particular to a grass trimmer.
Related Art
Green vegetation is a necessary environment key factor of human being, and a greening concept is more and more poplar. No matter a golf course, a football field, a manor, a yard of a villa, or a common residential quarter, a green turf is everywhere, and brings vitality and energy to people's life. Bu without managing, these turfs will become fluctuated and disordered.
As a garden tool for managing the turf, a grass trimmer is more and more popular among users. Usually, the grass trimmer drives a grass trimming line to rotate to trim grass, and generally comprises an extending rod extending longitudinally, a grass trimming head at one end of the extending rod, a handle arranged at the extending rod and spaced from the grass trimming head by certain distance and a motor driving the grass trimming head to rotate, the grass trimming head includes a base, a cap matched with the base and a spool arranged between the base and the cap, and the grass trimming line winds the spool and extends from the base. During working, the grass trimming head is driven to rotate to drive the grass trimming line to synchronously rotate so as to trim the grass.
The grass trimmer generally has two use states, one state is a conventional grass trimming state, in which a plane formed by rotating of the grass trimming line is parallel with the ground to manage large pieces of lawn fast; and the other state is an edge trimming state, in which a plane formed by rotating of the grass trimming line is vertical to the ground to manage the lawn at the edge of a road.
Since the grass trimming line rotates to trim the grass, the tail end of the grass trimming line is very easy to wear, the worn grass trimming line cannot reach a required grass trimming radius, and a grass trimming efficiency is greatly reduced. Therefore, a cord delivering mechanism is required on the grass trimmer so as to adjust the length of the grass trimming line extending out of the base at proper time.
Usually, there are two types of cord delivering mechanisms, one kind cord delivering mechanisms is an startup and shutdown automatic cord delivering mechanism, just as the name implies, the startup and shutdown automatic cord delivering mechanism will automatically pay off during startup and shutdown every time without extra operation, but exactly due to the cord delivering during startup and shutdown every time, the wear of the grass trimming line is very severe, the other kind of cord delivering mechanisms is a knocking cord delivering mechanism, having a triggering part protruding out of the cap, during use, the cap knocks on the ground to trigger cord delivering, its main disadvantage is that when the grass trimmer performs edge trimming operation, the grass trimmer needs to be reversed to enable the cap to knock the ground so as to pay off, which results in not only interruption of the grass trimming work but also complex operation.
In the other cord delivering mechanism, an operation part independent of a main switch is arranged at a holding part, movement of the operation part is transmitted to the spool by a transmission connector, so as to cause the spool to generate a speed difference relative to the base to pay off. But the movement of the manual operation part cannot be transmitted to the spool unless such kind of manual cord delivering mechanism is equipped with a transmission part basically penetrating through the extending rod longitudinally extending. Therefore, relative to the extending rod longitudinally extending, the transmission part is set to be telescopic or detachable, but the transmission part is complex in setting structure and not guaranteed in reliability.
The other cord delivering mechanism comprises an operation part allowing an operator to operate, the operation part controls and moves a steel rope arranged on the extending rod, the steel rope is driven to drive the spool to release a driving device of the grass trimming line. The operator can realize manual cord delivering of the spool by operating the operation part, but in order to meet an operation comfort demand, the extending rod is usually made very long, causing great increase of a packaging size of the grass trimmer, inconvenience in transportation and increase in transportation cost.